1. Field of the Invention
The present invention relates to a signal modulation apparatus, a signal modulation method and a computer program product thereof. More specifically, the present invention relates to a signal modulation apparatus, a signal modulation method and a computer program product thereof for use in a communication framework including a plurality of F communication systems.
2. Descriptions of the Related Art
With continuous advancement in science and technology, people are imposing ever higher requirements on communications. Over recent years, more importance is being attached to convenience of communications in addition to requirements on quality of communications. Wireless communications are advantageous in that they provide higher mobility by obviating the need of physical communication network wiring. Therefore, wireless-communication-enabled products such as mobile phones, notebook computers and the like are more popular and have become the mainstream products in the consumer electronics market.
However, wireless communication systems communicate information through radio waves in the air, so the communication environment in which they operate is rather complex and liable to interference. Moreover, when two different wireless communication systems, e.g. a global system for mobile communication (GSM) and a worldwide interoperability for microwave access (WiMAX) system, may also be exposed to interference from each other because their antennas are too close to cause problems with communication quality.
To describe the problem of signal interference in more detail, a schematic view illustrating signal interference of two communication systems is illustrated in FIG. 1. The horizontal axis f represents frequencies occupied by the communication systems, the vertical axis S represents a frequency spectrum of a first communication system, and the vertical axis S′ represents a frequency spectrum of a second communication system. It can be seen from FIG. 1 that a signal 11 transmitted by the first communication system and a signal 12 transmitted by the second communication system have an overlapped region which is known as an interference region 13. When the area of the interference region 13 is larger, the interference between the signals transmitted by the first and the second communication systems respectively will be more serious.
A conventional solution to this problem is just to measure the interference level on site by technicians and then modulate the transmitting power of respective antennas to avoid signal interference of the two communication systems to each other. This solution is effective, but it still consumes additional and extensive manpower and time, causing increased operational cost of the wireless communication service providers.
In view of this, a need still remains in the art to effectively mitigate signal interference between two communication systems due to too close deployment of respective antennas without consuming excessive additional manpower and time.